Question

Say we have a population, with Ne = 100, containing two alleles, A1 and A2 at frequencies 0.6 and 0.4, respectively. We leave this population alone for 10000 generations (keeping its size constant), then come back to find that the allele frequencies are still 0.6 and 0.4.
a) Explain why this would be evidence that selection is acting in this population.


b) Which genotype would you expect to have the highest fitness in this case? Explain.

Answer 1

Answer:

a. It is found that even after 10000 generations, the allele frequency is still the same, that is, 0.6 and 0.4. This shows random mating population. None of the other factors like emigration, immigration, mutation, and others are operating. On the basis of Hardy-Weinberg law, if a population stays in random mating with no factors operating, in such situation, allele frequency will stay same from generation to generation. That is why in the given case, the allele frequency is still similar.  

b. In a random mating population, all the genotypes are identically fit. In such populations, the phenomenon of natural selection does not take place.